An ink-jet recording apparatus is usually equipped with an ink-jet recording head which is mounted on a carriage and moved in the widthwise direction of recording paper, and paper feed means for moving the recording paper in the direction orthogonal to the traveling direction of the recording head. On the basis of print data, ink droplets are ejected from the recording head, thus recording the data on the recording paper.
The recording head is mounted on the carriage, and is capable of ejecting ink droplets of, for example, black, yellow, cyan, magenta, etc. Accordingly, the ink-jet recording apparatus enables full-color printing by changing the proportions of ink types, as well as effecting text printing with black ink.
Incidentally, in order to effect a comparatively-high volume of printing, a recording apparatus of this type supplied for, for example, an office or business purpose, requires use of high-volume ink cartridges. To this end, there has been provided a recording apparatus, in which ink cartridges (referred to also as main tanks) are fitted to a cartridge holder provided, for example, to an apparatus main body.
In the recording apparatus, sub-tanks are disposed on the carriage having the recording head, and the respective sub-tanks are replenished with ink from corresponding ink cartridges by way of ink supply tubes. The sub-tanks, in turn, supply ink to the recording head.
Recently, growing demand exists for a large-size recording apparatus capable of effecting printing on larger-size paper, in which a carriage travels a longer scan distance. In order to improve throughput of such a recording apparatus, a larger number of nozzles are provided in a recording head.
Further, demand exists for a recording apparatus which sequentially supplies ink to the respective sub-tanks mounted on the carriage from corresponding ink cartridges while performing printing operation, in order to improve throughput, and which stably supplies ink from the respective sub-tanks to the recording head.
In such a recording apparatus, since the carriage travels over a longer scan distance, the lengths of respective ink supply tubes for connecting the ink cartridges to the sub-tanks correspondingly to ink types inevitably increase.
Further, as mentioned above, a larger number of nozzles are provided in the recording head. Hence, such a recording apparatus encounters a technical problem of deficient ink supply to the sub-tanks because the recording head consumes a large quantity of ink, and an increase in the dynamic pressure (i.e., pressure loss) of ink is likely to occur within each of the ink supply tubes interconnecting the ink cartridges and the sub-tanks.
As one measure to prevent this technical problem, there may be employed, for example, a construction in which air pressure is applied to the ink cartridges to forcibly inducing ink flows from the ink cartridges to the sub-tanks under air pressure. This construction makes it possible to supply a sufficient amount of ink to the sub-tanks.
An ink cartridge used in the thus constructed recording apparatus can preferably adopt such constitution that a case defining an outer shell of the ink cartridge is formed so that the inside of the case is hermetically sealed, and an ink pack formed from flexible material and sealingly filled with ink is housed in the case.
The ink pack in the thus constructed ink cartridge acts so that ink is pushed out by pressurized air applied to the inside of the case and fed out to the recording head mounted on the carriage.